The invention relates to a method in winding of a web, in which method the web is wound onto a core while supported by winding drums, in which method the web is cut by a cutting device, a finished web roll is removed by means of a transfer device, a new core is moved to a space between the winding drums, and in which method the winding is stopped to remove the finished roll and to start a new roll.
The invention also relates to a device in winding of a web, which device comprises winding drums, on support and by means of which the web is wound onto a core into a web roll, which device further comprises a cutting device for cutting the web and a transfer device for removing the finished web roll and a core transfer device for taking a new core to a winding position onto support of a winding drum.
When forming a roll/rolls in winding of a web in a slitter-winder, in a situation of web set change, it is always necessary to stop the winding before starting a new winding operation and to remove the set and, after a new core has been positioned on the two-drum winder, the winding must be started again. Today, the set change time in winding of a web is in practice about 30 to 70 seconds when mechanized arrangements are used and about 2 minutes when cores are positioned manually. In this description, when referring to a core, one or more cores or other reel spools are meant around which a web, in particular a paper or board web is wound into a web roll/web rolls. By the two-drum winder (two-drum slitter-winder) is meant a winder of the two-drum type in which a web roll is formed on support of winding drums, which winding drums can be drums or sets of belt drums.
A problem in today's set change technique is the long set change time, which lowers capacity.
Corresponding prior-art methods and devices have often suffered from the drawback that it has not been possible to control the quality at the start of winding sufficiently well. For example, wrinkles may have been produced at the roll start or bottom because of problems caused by a long cut length in passing the end of the web onto a core, to which the end of the web is attached, for example, with glue or with a double-faced tape.
With respect to the prior art, reference is made to U.S. Pat. No. 3,841,578, which describes a method and a device for continuously winding material webs into individual rolls. The apparatus used in this prior-art arrangement may comprise a take-up roll, which is placed on the front side of a gap between winding drums, by which an empty reel coming from a reel storage can be pushed through the gap between the winding drums to the winding side of them.
With respect to the prior art, reference is also made to Finnish patent No. 81 551, which describes a method and a device in winding of a web. In the method, a finished web roll is removed by means of a lowering device. Partly substantially simultaneously with the roll lowering movement a new core is moved into a gap between a first winding drum and a second winding drum. The web is cut and the cut end of the web is attached to the core. In order to remove a finished roll and to start a new winding operation, the winding is slowed down to the set change speed and a rider roll is raised off the finished roll and moved rearwards relative to the finished roll. A set of belt drums is moved in a lateral direction and a new core is moved into a space defined by the first winding drum, the first drum in the set of belt drums, and the finished roll. The set of belt drums is moved back in the lateral direction and the rider roll is moved towards the new core, the rider roll being arranged to push at the same time the finished roll away from the first winding drum. Substantially at the same time, the second drum in the set of belt drums is lowered in a vertical direction, in which connection the finished roll is arranged to be moved to the lowering device. A problem with this prior-art arrangement is that, because of complexity, the structure becomes rather expensive. Moreover, this prior-art arrangement does not actually propose any arrangement for controlled holding of the core when the set of drums is brought into contact with it.